Process of printing in greasy inks with gelatin printing surfaces



Patented Mar. 6, 1928.

UNITED STATES OTTO TBEICHEL, ()Ili BERLIN, GERMANY.

YROCESS OF PRINTING IN GBEASY INKS WITH GELATIN PRINTING SURFACES.

No Drawing. Application filed November 80, 1928, Serial No. 151,826, andin Germany December 18, 19 25.

It is well known that in the process of printing in greasyinks withgelatin printing sur aces, more or less elevated reliefs are formedunder the action of the wetting medium, said reliefs being undesirablein that they cause trouble during the distribution of the ink as'well asduring the actual printing. Several attempts have already been made toremove this drawback but none of them have had the desired result.

The present invention strikes out in a new direction, in that the evilis attacked at the root and the gelatin is treated at the outsetin sucha manner that its swelling capacity is reduced. Y

The process consists in this that to the gelatin are added by way of thewetting medium, substances which reduce the swelling property of thegelatin, for instance solutions of sodium sulphate. A decinormalsolution of. the wetting medium is mentioned as a proportion which hasproved satisfactory in prailtice.

It is obvious that by means of this treatment also the subsequentlyformed relief,

which can never be entirely avoided, is very considerably reduced. It istrue that in the reliefs so produced, the high lights also take upgreasy inks; this'is obviated according to the invention 'by increasingthe temperature of the wetting medium. Normally a wetting medium at 22is employed. According to the invention, temperatures of about 25 andover are employed. A further advantage of the new process consists inthis that in the. well-known interdependence of the relief with thegradation, the latter can be adjusted to any desired degree. In theappended claims, by the term a substance having the property of reducingor delaying the swelling of the gelatin I n 1 e'an to include allsaltssuch as sulphates; cltrates, acetates, salts of di- .and multivalentcations, etc. all of which possess the well known and common property ofreducmg or delaying gelatin swelling.

Having now particularly described and ascertained the nature of-my saidinvention and in what manner the same is to be per-- formed, I declarethat what'I claim is:'- 1. In the process of printing with greasy mks ongelatin printing surfaces, the step consisting in wetting the gelatinprinting surface with a wetting medium containing a substance having theproperty of reducing or delaying the swelling of the gelatin.

2. In the process of printing with greasy inli s on gelatin printingsurfaces, the step consisting in treating the gelatin with a substancehaving the property of reducing or delaying the swelling of the gelatin.

3. In the process of printing with greasy inks on gelatin printinsurfaces, the step consisting in wetting 518 gelatin printing surfacewith a wetting medium containing sodium sulphate, for the purpose setforth.-

4. In the process of printing with greasy inks on gedatin printingsurfaces, the step consisting in wetting the'gelatin printing surfacewith a wetting medium heated to. a temperature above 22 0.,andcontaining a substance having the propert of reducing or delayingtheswelling of the gelatin for the purpose set forth.

Intestimony whereof I have signed my name to this specification.

' 7 Dim. o. TREICHEL.

